The present invention relates to an electronic sensor unit for a motor vehicle, for detecting a noncontact actuation of a door or hatch on a motor vehicle.
The electronic sensor unit comprises a control and evaluation system, which is coupled to a capacitive sensor electrode for detecting a capacitance change to the sensor electrode during an actuation, or the approach by a user, respectively. The sensor unit furthermore comprises a lighting system, with which a target region on a substrate can be marked, wherein this target region should indicate to the user the region in which a noncontact actuation of the door or hatch is at all possible.
A control and evaluation system coupled to the sensor electrode detects a capacitance change to the sensor electrode in relation to a reference potential, in that it periodically charges and discharges the sensor electrode with a predefined frequency, and evaluates at least one parameter of a current and voltage course dependent on the periodic charging and discharging of the sensor electrode, in order to detect the capacitance change. The sensor electrode reacts thereby to the approach of objects by a capacitance change of the capacitor formed by the sensor electrode and the object This can be traced back to the fact, at the core, that the capacitance of a capacitor is dependent on its plate spacing. Normally, its capacitance increases as the object comes closer to the sensor electrode.
Capacitive sensor assemblies having sensor electrodes, with which the introduction of an object into a space in front of the electrode is detected, are known in the prior art.
From DE 10 2008 025 669 A1 an actuation device for a vehicle locking system is known, which comprises, among other things, an optical system, with which a light beam is projected onto a substrate. When this light beam is interrupted by an object, this signalizes that a door or hatch is to be unlocked. The actuation device known from the aforementioned document comprises a plurality of components, distributed over the entire vehicle. As a result, the installation of the device is cost-intensive, and prone to installation error, by way of example, in the wiring of the plurality of structural components.
It is therefor the objective of the present invention to provide a structurally simple electronic sensor assembly, which can be installed simply and quickly.
This objective is achieved in accordance with the invention by the features of claim 1.